I want to send a alerts when ever anyone coments on the newsfeed. 
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Although currently to set an alert on a newsfeed you have to set the alert on a microfeed.
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Instead of all the information that is sent in the email, I just want the content to be sent. How would I do this?
You are Online so you can not change anything Server-Side, with: https://blogs.msdn.microsoft.com/sharepointdeveloperdocs/2007/12/07/customizing-alert-notifications-and-alert-templates-in-windows-sharepoint-services-3-0/
Your only option then is to create a Workflow and send an email.
